writeback: introduce wbc.for_background
It will lower the flush priority for NFS, and maybe more in future.
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Cc: Trond Myklebust <Trond.Myklebust@netapp.com>
Cc: Jens Axboe <jens.axboe@oracle.com>
Cc: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index 53eb26c..c84b5cc 100644
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -178,7 +178,7 @@
{
if (wbc->for_reclaim)
return FLUSH_HIGHPRI | FLUSH_STABLE;
- if (wbc->for_kupdate)
+ if (wbc->for_kupdate || wbc->for_background)
return FLUSH_LOWPRI;
return 0;
}